Pulsatile drug release

ABSTRACT

In one aspect, the present invention is concerned with a treatment where it is desired that an active agent is designed to be released in a pulse at a time point some time after administration of the active agent. The present invention is particularly suited to administering an agent which may be released while a subject is sleeping. As well as treating certain conditions by a particular regime, the invention also provides novel formulations for a delayed, followed by a pulsed release of drug.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a United States Application under 35 U.S.C. 371 claiming the benefit of PCT Application No. PCT/GB2011/000306, filed on Mar. 4, 2011, which claims the benefit of GB Application No. 1003766.1, filed on Mar. 5, 2010, the contents of each of which are incorporated herein by reference.

FIELD OF INVENTION

In one aspect, the present invention is concerned with a treatment where it is desired that an active agent is designed to be released in a pulse at a time point some time after administration of the active agent. The present invention is particularly suited to administering an agent which may be released whilst a subject is sleeping. As well as treating certain conditions by a particular regime, the invention also provides novel formulations for a delayed, followed by a pulsed release of drug.

BACKGROUND TO THE INVENTION

Time-dependent release mechanisms of drugs have been described in the literature for tablet, pellet and capsule formulation utilising a wide range of physicochemical and physicomechanical strategies. The common feature of all such formulations is that they are activated by contact with fluids following ingestion by the patient and the drug will be released at the predetermined time after administration. Only after the formulations come into contact with gastric fluids does the ‘clock’ start. Drug release subsequently takes place at a predicted time, although it will be appreciated that since the dosage unit will be travelling through the GI tract during the lag period, drug release will necessarily be at some unknown GI tract site. Using such formulation strategies, it will be possible to design delivery systems capable of releasing drugs according to chronotherapeutic principles and targeting release to the circadian rhythm of disease states (Stevens H N E, Chronopharmaceutical Drug Delivery. J Pharm Pharmac., 50 (s) 5 (1998))

However, many of the formulations in the art rely on complex structures which can add to the cost of the manufacture of the drug and/or can be subject to malfunction leading to incorrect/inappropriate administration of the drug.

It is amongst the objects of the present invention to obviate and/or mitigate at least one of the aforementioned disadvantages.

It is amongst the objects of the present invention to provide a formulation which may be easily and/or cheaply manufactured and which allows for an active agent to be administered in a short pulse, following a period of delay following administration.

SUMMARY OF INVENTION

The present inventors recognised a need to be able to administer, for example, a pharmaceutically active agent to a subject in a manner such that a delayed release of the pharmaceutically active ingredient could be achieved, followed by a pulsed delivery of the agent. Although this may have been possible using prior device/methods known in the art, many such devices/methods were highly complex and there is distinct advantage in providing a simpler press-coated tablet formulation.

One particularly preferred embodiment relates to treating subjects who wake during the night, but have no or little difficulty in initially falling asleep, commonly termed sleep maintenance insomnia. In a preferred embodiment therefore, the formulations of the present invention are for treating sleep maintenance insomnia. Such formulations therefore comprise a pharmaceutically active agent for inducing and/or facilitating sleep. Typically this may be a sedative or hypnotic agent, such as a benzodiazepine, chloral hydrate, melatonin and analogues thereof, zolpidem, zopiclone or zaleplon.

Thus, in a first aspect, the present invention provides a sleep inducing and/or maintaining formulation agent such as a sedative or hypnotic agent, formulated as a component of a press-coated tablet for treating sleep maintenance insomnia, wherein the formulation is intended to be administered immediately prior to a subject going to sleep (i.e. when a subject goes to bed at night for a prolonged period of sleep, such as 6-10 hours and hence is distinguished over shorter sleeping periods) and wherein the hypnotic agent is substantially not released from the formulation for a period between 1-8 hours, such as 1.5-4 hours after administration of the formulation to the subject and thereafter the agent is released from the formulation as a pulse such that at least 70-90%, for example 80% of the agent within the formulation is released within 5-80 mins, such as 10-45, or 10-30 mins.

In a further aspect there is provided a method of treating sleep maintenance insomnia, the method comprising administering a press-coated tablet comprising a sleep inducing agent, such as a sedative or hypnotic agent to a subject, immediately before the subject intends sleeping, wherein the formulation substantially delays release of the drug for 1-8 hours, such as 1.5-4 hours following administration of the formulation and thereafter the drug is released in a pulse over a period of 5-80 mins, such as 10-45 or 10-30 mins.

Typically delayed release of the active agent is achieved by providing a press-coated tablet comprising a delayed release layer surrounding a core comprising the active agent. The delayed release layer may comprise a wax and a low-substituted hydroxypropyl cellulose (L-HPC), such as LH-11, or LH-21.

In a further aspect, the present invention provides a press-coated tablet formulation for a delayed, followed by a pulsed release of an active agent, the tablet comprising

(a) a core comprising the active agent(s) together with an excipient(s); and

(b) a delayed release layer surrounding the core and comprising a wax and L-HPC in a ratio of 40:60 to 60:40 w/w; wherein the delayed release layer substantially delays release of the active agent within the core for between 1-8 hours, such as 1.5-4 hours after administration of the tablet by a subject and thereafter a pulsed release of the active agent from the core occurs, such that at least 70% of the active agent in the core is released within 5-80 mins, such as 10-40 or 10-30 mins.

The active agents of the above aspect include any active agent for which delayed followed by pulsed release is desirable. In a preferred embodiment of the invention, the active agent is a pharmaceutically acceptable active agent and includes pharmaceutical and veterinary active agents (often referred to as drugs). In other embodiments, the active agent includes agrichemical agents (such as fertilizers, herbicides, pesticides and fungicides), active agent used in the exterminating industry (such as toxins and poisons), and active agents used in industrial manufacturing (such as catalysts or catalytic quenchers).

The press-coated tablets of the present invention may be used to treat one or more of the following conditions/disorders or diseases:

Central Nervous System disorders, e.g. Neurogenic pain, stroke, dementia, Alzheimer's disease, Parkinson's disease, neuronal degeneration, meningitis, spinal cord injury, cerebral vasospasm, amyotrophic lateral sclerosis

Cardiovascular disease, hypertension, atherosclerosis, angina, arterial obstruction, peripheral arterial disease, myocardial pathology, Arrhythmia, Acute Myocardial Infarction, Angina, Cardiomyopathy, Congestive heart failure, Coronary artery disease (CAD), Carotid artery disease, Endocarditis, Hypercholesterolemia, hyperlipidemia, Peripheral artery disease (PAD) Genitourinary Disorders; erectile dysfunction, urinary organ diseases benign prostatic hypertrophy (BPH), Renal tubular acidosis, diabetic nephropathy, glomerulonephritis, glomerulosclerosis, urinary tract infection, faecal incontinence Ocular disease glaucoma, blephartitis, ocular hypertension, retinopathy, conjunctivitis, scleritis, retinitis, keratitis, corneal ulcer, iritis, Chorioretinal inflammation, macular edema, Xerophthalmia Pulmonary disease asthma, pulmonary hypertension, acute respiratory distress syndrome, COPD, emphysema, pneumonia, tuberculosis, bronchitis, Acute Bronchitis, Bronchiectasis, Bronchiolitis, Bronchopulmonary Dysplasia, Byssinosis, Coccidioidomycosis (Cocci), Cystic Fibrosis, Influenza, Lung Cancer, Mesothelioma Metabolic diseases; Hypercalciuria, Hyperglycemia, Hyperinsulinemic hypoglycemia, Hyperinsulinism, Hyperlysinuria, Hypoglycemia Exocrine and Endocrine; Addison's disease, Hypoaldosteronism, cushing's syndrome, diabetes, Goitre, Hyperthyroidism, Hypothyroidism, Thyroiditis, pancreatitis Hepatic disorders, Hepatitis, Non-alcoholic fatty liver disease, cirrhosis, hepatic cancer, Primary sclerosing cholangitis, primary biliary cirrhosis, Budd-Chiari syndrome, Autoimmune and Inflammatory diseases, multiple sclerosis rheumatoid arthritis, psoriasis, diabetes, sarcoidosis, Addison's Disease, Alopecia areata, Amyotrophic Lateral Sclerosis, Ankylosing Spondylitis, polyarticular Arthritis, Atopic allergy, topic Dermatitis, Autoimmune hepatitis, Celiac disease, Chagas disease, Coeliac Disease, Cogan syndrome, Crohns Disease, Cushing's Syndrome, Diabetes mellitus type 1, Endometriosis, Eosinophilic fasciitis, Fibromyalgia/Fibromyositis, Gastritis, Glomerulonephritis, Graves' disease. Guillain-Barrë syndrome (GBS), Hashimoto's encephalitis, Hashimoto's thyroiditis, Haemolytic anaemia, Idiopathic Inflammatory Demyelinating Diseases, Idiopathic pulmonary fibrosis, interstitial cystitis, Juvenile idiopathic arthritis, Juvenile rheumatoid arthritis, Kawasaki's Disease, Lichen sclerosus, Lupus erythematosus, Ménière's disease, Myasthenia gravis, myositis, Narcolepsy, Pernicious anaemia, Perivenous encephalomyelitis, Polymyalgia rheumatica, Primary biliary cirrhosis, Psoriatic Arthritis, Reiter's syndrome, Rheumatoid fever, Sarcoidosis, Schizophrenia, Sjögren's syndrome, Spondyloarthropathy, Ulcerative Colitis Musculoskeletal disorders: osteoarthritis, osteoporosis, Osteonecrosis, Arthritis, Paget's Disease Bursitis, Costochondritis, Tendonitis Skin disorders; Acne, alopecia, candidiasis, celluliltis, dermatitis, eczema, epidermolysis bullosa, erythrasma, herpes, erysipelas, Folliculitis, impetigo, ringworm, scabies, Tinea, Trichomycosis ENT disorders; Otitis, sinusitis, laryngitis, pharyngitis, laryngitis, meniere's disease, labyrinthitis, Others: acute and chronic pain, viral infection, cancer, laryngitis, mastoiditis, myringitis, otitis media, rhinitis, sinusitis, Sialadenitis, Retropharyngeal Abscess, Tonsillopharyngitis, Gastro-Intestinal Disorders Irritable bowel syndrome (IBS) necrotizing entercolitis (NEC) non-ulcer dyspepsia, chronic intestinal pseudo-obstruction, functional dyspepsia, colonic pseudo-obstructioduodenogastric reflux, gastroesophageal reflux disease, ileus inflammation, gastroparesis, heartburn, constipation—(e.g. constipation associated with use for medications such as opioids), colorectal cancer, colonic polyps, diverticulitis, colorectal cancer, Barretts Esophagus, Bleeding in the Digestive Tract, Celiac Disease, Colon Polyps, Constipation, Crohns Disease, Cyclic Vomiting Syndrome, Delayed Gastric Emptying (Gastroparesis), Diarrhea, Diverticulosis, Duodenal Ulcers, Fecal Incontinence, Gallstones, Gas in the Digestive Tract, Gastritis, Gastroesophageal Reflux Disease (GERD), Heartburn, Hiatal Hernia, Hemochromatosis, Hemorrhoids, Hiatal Hernia, Hirschsprung's Disease, Indigestion, Inguinal Hernia, Lactose Intolerance, Peptic Ulcers, Polyps, Porphyria, Primary Biliary Cirrhosis, Primary Sclerosing Cholangitis, Proctitis, Rapid Gastric Emptying, Short Bowel Syndrome, Stomach Ulcers, Ulcerative Colitis, Ulcers, Whipples Disease Exemplary active agents for use in the pharmaceutical and veterinary applications of the invention include analgesics, anaesthetics, anticonvulsants, antidiabetic agents, antihistamines, anti-infectives, antineoplastics, antiparkinsonian agents, antirheumatic agents, appetite stimulants, appetite suppressants, blood modifiers, bone metabolism modifiers, cardiovascular agents, central nervous system depressants, central nervous system stimulants, decongestants, dopamine receptor agonists, electrolytes, gastrointestinal agents, immunomodulators, muscle relaxants, narcotics, parasympathomimetics, sympathomimetics, sedatives, and hypnotics. Said Active Agent or Agents May be Selected from the Following: Gastro Drugs Antacids—aluminium hydroxide, magnesium carbonate, magnesium trisilicate, hydrotalcite, simeticonealginates, Antispasmodics—atropine sulphate, dicycloverine hydrochloride, hyoscine butylbromine, propantheline bromide, alverine citrate, mebeverine hydrochloride, Motility stimulants—metoclorpramide, domperidone H2—Receptor antagonists—Cimetidine, famotidinenizatidine, ranitidine Antimuscarinics—pirenzepine Chelates—Tripotassium dicitratbismuthate, sucralfate, Prostaglandin analogues—misoprostol Aminosalicylates—balsazide sodium, mesalazine, olsalazine, sulphasalazine Corticosteroids—beclometasone dipropionate, budenoside, hydrocortisone, prednisolone, Affecting immune response—ciclosporin, mercaptopurine, methotrexate, adalimumab, infliximab Stimulant Laxatives—bisacodyl, dantron, docusate, sodium picosulfate, Drugs affecting biliary composition and flow—ursodeoxycholic acid Bile acids sequestrants—colestyramine, Oxyphencyclimine, Camylofin, Mebeverine, Trimebutine, Rociverine, Dicycloverine, Dihexyverine, Difemerine, Piperidolate Benzilone, Mepenzolate, Pipenzolate, Glycopyrronium, Oxyphenonium, Penthienate, Methantheline, Propantheline, Otilonium bromide, Tridihexethyl, Isopropamide, Hexocyclium, Poldine, Bevonium, Diphemanil, Tiemonium iodide, Prifinium bromide, Timepidium bromide, Fenpiverinium Papaverine, Drotaverine, Moxaverine 5-HT3 antagonists (Alosetron, Cilansetron), 5-HT4 agonists (Mosapride, Prucalopride, Tegaserod) Fenpiprane, Diisopromine, Chlorbenzoxamine, Pinaverium, Fenoverine, Idanpramine, Proxazole, Alverine, Trepibutone, Isometheptene, Caroverine, Phloroglucinol, Silicones, Trimethyldiphenylpropylamine Atropine, Hyoscyamine Scopolamine (Butylscopolamine, Methylscopolamine), Methylatropine, Fentonium, Cimetropium bromide primarily dopamine antagonists (Metoclopramide/Bromopride, Clebopride, Domperidone, Alizapride), 5-HT4 agonists (Cinitapride, Cisapride), Proton pump inhibitors Omeprazole, lansoprazole, pantoprazole, esomeprazole, rabeprazole sodium, opioids and opioid receptor antagonists—e.g. codeine, morphine, loperamide, diphenoxylate, methylnaltrexone bromide Analgesic Acetaminophen Diclofenac Diflunisal Etodolac Fenoprofen Flurbiprofen Ibuprofen Indomethacin Ketoprofen Ketorolac Meclofenamate Mefenamic Acid Meloxicam Nabumetone Naproxen Oxaprozin Phenylbutazone Piroxicam Sulindac Tolmetin Celecoxib Buprenorphine Butorphanol Codeine Hydrocodone Hydromorphone Levorphanol Meperidine Methadone Morphine Nalbuphine Oxycodone Oxymorphone Pentazocine, Propoxyphene Tramadol codeine Sleep Drugs Hypnotics—Nitrazepam, Flurazepam, Loprazolam, Lormetazepam, Temazepam, Zaleplon, Zolpidem, Zopiclone, Chloral Hydrate, Triclofos, Clomethiazole, Quazepam, triazolam Estazolam Clonazepam, Alprazolam, Eszopiclone, Rozerem, Trazodone, Amitriptyline Doxepin, Benzodiazepine drugs, melatonin, diphenhydramine and herbal remedies such as Valerian Cardiovascular Medicines Cardiac glycosides—Digoxin, digitoxin, Phosphodiesterase Inhibitors—enoximone, milrinone Thiazides and related diuretics—bendroflumethiazide, chlortalidone, cyclopenthiazide, inapamide, metolazone, xipamide Diuretics—furosemide, bumetanide, torasemide, Potassium sparing diuretics and aldosterone antagonists—amiloride hydrochloride, triamterene, weplerenone, spironolactone, Osmotic diuretics—mannitol Drugs for arrhythmias—adenosine, amiodarone hydrochloride, disopyramide, flecainide acetate, propafenone hydrochloride, lidocaine hydrochloride, Beta adrenoreceptor blocking drugs—propanalol, atenolol, acebutolol, bisprolol fumarate, carvedilol, celiprolol, esmolol, lebatolol, metoprolol tartrate, nadolol, nebivolol, oxprenolol, pindolol, solatol, timolol, Hypertension—ambrisentan, bosentan, diazoxide, hydralazine, iloprost, minoxidil, sildenafil, sitaxentan, sodium nitroprusside, clonidine, methyldopa, moxonidine, guanethidine monosulphate, doxazosin, indoramin, prazosin, terazosin, phenoxybenzamine, phentolamine mesilate, Drugs affecting the renin-angiotensin system—Captropril, Cilazapril, Enalapril Maleate, Fosinopril, Imidapril, Lisinopril, Moexipril, Perindopril Erbumine, Quinapril, Ramipril, Trandolapril, Candesartan Cilexetil, Eprosartan, Irbesartan, Losartan, Olmesartan Medoxomil, Telmisartan, Valsartan, Aliskiren. Nitrates, calcium channel Blockers and antianginal drugs—Glyceryl trinitrate, Isosorbide Dinitrate, Isosorbide Mononitrate, Amlodipine, Diltiazem, Felodipine, Isradipine, Lacidipine, Lercanidipine, Nicardipine, Nifedipine, Nimodipine, Verapamil, Ivabradine, Nicorandil, Ranolazine, Peripheral Vasodilators and related drugs—Cilostazol, Inositol Nicotinate, Moxisylyte, Naftidrofuryl Oxalate, Pentoxifylline, Sympathomimetics—Dopamine, Dopexamine, Ephedrine, Metaraminol, Noradrenaline Acid Tartrate, Norephidrine Bitartrate, Phenylephidrine, Anticoagulants and Protamine—Heparin, Bemiparin, Dalteparin, Enoxaparin, Tinzaparin, Danaparoid, Bivalirudin, Lepirudin, Epoprostenol, Fondaprinux, Warfarin, Acenocoumarol, Phenindione, Dabigatran Etexilate, Rivaroxaban, Protamine Sulphate, Antiplatelet Drugs—Abciximab, Asprin, Clopidogrel, Dipyridamole, Eptifibatide, Prasugrel, Tirofiban, Fibrinolytic and antifibrinolytic Drugs—Alteplase, Reteplase, Streptokinase, Tenecteplase, Urokinase, Etamsylate, Tranexamic Acid, Lipid Regulating Drugs—Atorvastatin, Fluvastatin, Pravastatin, Rosuvastatin, Simvastatin, Colesevam, Colestyramine, Colestipol, Ezetimibe, Bezafibrate, Ciprofibrate, Fenofibrate, Gemfibrozyl, Acipmox, Nictotinic Acid, Omega three fatty acid compounds, Ethanolamine Oleate, Sodium Tetradecyl Suphate. CNS Drugs—Benperidol, Chlorpromazine, Flupentixol, Haloperidol, Levomepromazine, Pericyazine, Perphenazine, Pimozide, Prochlorperazine, Promazine, Sulpiride, Trifluoperazine, Zuclopenthixol, Amisulpride, Aripiprazole, Clozapine, Olanzapine, Paliperidone, Quetiapine, Riperidone, Sertindole, Zotepine, Flupentixol, Fluphenazine, Olanzapine Embonate, Pipotiazine Palmitate, Risperidone, Zuclopenthixol Decanoate, Carbamazepine, Valproate, Valproic acid, Lithium Carbonate, Lithium Citrate, Amitriptyline, Clomipramine, Dosulepin, Imipramine, Lofepramine, Nortriptyline, Trimipramine, mianserin, Trazodone, Phenelzine, Isocarboxazid, Tranylcypromine, Moclobemide, Citalopram, Escitalopram, Fluoxetine, Fluvoxamine, Paroxetine, Sertraline, Agomelatine, Duloxetine, Flupentixol, Mirtazapine, Reboxetine, Trytophan, Venflaxine, Atomoxetine, Dexametamine, Methylphenidate, Modafinil, Eslicarbazepine, Ocarbazepene, Ethosuximide, Gabapentin, Pregabalin, Lacosamide, Lamotrigine, Levetiracetam, Phenobarbital, Primidone, Phenytoin, Rufinamide, Tiagabine, Topiramate, Vigabatrin, Zonisamide, ropinirole, Rotigotine, Co-Beneldopa, Levodopa, Co-Careldopa, Rasagiline, Selegiline, Entacapone, Tolcapone, Amantidine, Orphenadrine, Procyclidine, Trihexyphenidyl, Haloperidol, Piracetam, Riluzole, Tetrabenazine, Acamprosate, Disulfiram, Bupropion, Vareniciline, Buprenorphine, Lofexidine, Donepezil, Galantamine, Memantine, Rivastigimine. Anti-Infectives—Benzylpenicillin, Phenoxymethylpenicillin, Flucloxacillin, Temocillin, Amoxicillin, Ampicillin, Co-Amoxiclav, Co-Fluampicil, Piperacillin, Ticarcillin, Pivmecillinam, Cephalosporins, Cefaclor, Cefadroxil, Cefalexin, Cefixime, Cefotaxime, Cefradine, Ceftazidime, Cefuroxime, Ertapenem, Imipenem, Meropenem, Aztreonam, Tetracycline, Demeclocycline, Doxocycline, Lymecycline, Minocycline, Oxytetracycline, Tigecycline, Gentamicin, Amikacin, Neomycin, Tobramycin, Erythromycin, Azithromycin, Clarithromycin, Telithromycin, Clindamycin, Chloramphenicol, Fusidic Acid, Vancomycin, Teicoplanin, Daptomycin, Linezolid, Quinupristin, Colistin, Co-Trimoxazole, Sulpadiazine, Trimethoprim Capreomycin, Cycloserine, Ethambutol, Isoniazid, Pyrazinamide, Rifabutin, Rifampicin, Streptomycin, Dapsone, Clofazimine, Metronidazole, Tinidazole, Ciproflaxacin, Levoflaxacin, Moxifloxacin, Nalidixic Acid, Norflaxine, Orflaxacin, Nitrofurantoin, Methenamine Hippurate, Amphotericin, Anidulafungin, Caspofungin, Fluconazole, Flucytosine, Griseofluvin, Itraconzole, Ketoconazole, Micafungin, Nystatin, Posaconazole, Terbinafine, Voriconazole, Abacavir, Didanosine, Emtricitabine, Lamivudine, Stavudine, Tenofovir Disoproxil, Zidovudine, Atazanavir, Darunavir, Fosamprenavir, Indinavir, Lopinair, Nelfinavir, Ritonavir, Saquinavir, Tipranavir, Efavirenz, Etravirine, Nevarapine, Enfuvirtide, Maraviroc, Raltegravir, Aciclovir, Famciclovir, Inosine Pranobex, Valaciclovir, Cidofovir, Gangciclovir, Foscarnet, Valgangciclovir, Adefovir Dipivoxil, Entecavir, Telbivudine, Amantadine, Oseltamivir, Zanamivir, Palivizumab, Ribavirin, Artemether, Chloroquine, MefloquinePrimaquine, Proguanil, Pyrimethamine, Quinine, Doxycyclin, Diloxanide Furoate, Metronidaziole, Tinidazole, MepacrineSodium Stibogluconate, Atovaquone, Pentamidine Isetionate, Mebendazole, Piperazine, Other: Benztropine, procyclidine, biperiden, Amantadine, Bromocriptine, Pergolide, Entacapone, Tolcapone, Selegeline, Pramipexole, budesonide, formoterol, quetiapine fumarate, olanzapine, pioglitazone, montelukast, Zoledromic Acid, valsartan, latanoprost, Irbesartan, Clopidogrel, Atomoxetine, Dexamfetamine, Methylphenidate, Modafinil, Bleomycin, Dactinomycin, Daunorubicin, Idarubicin, Mitomycin, Mitoxantrone, Azacitidine, Capecitabine, Cladribine, Clofarabine, Cytarabine, Fludarabine, Flourouracil, Gemcitabine, mercaptopurine, methotrexate, Nelarabine, Pemetrexed, Raltitrexed, Thioguanine, Apomorphine, Betamethasone, Cortisone, Deflazacort, Dexamethosone, Hydrocortisone, Methylprednisolone, Prednisolone, Triamcinolone, Ciclosporine, Sirolimus, Tacrolimus, Interferon Alpha, Interferon Beta.

In a particularly preferred embodiment the active agent is designed to treat sleep maintenance insomnia and as such the active agent is a sedative or hypnotic, such as zolpidem, Zaleplon or Zopiclone.

The term “active agent” is understood to include solvates (including hydrates) of the free compound or salt, crystalline and non-crystalline forms, as well as various polymorphs. For example, the active agent can include all optical isomers of the compounds and all pharmaceutically acceptable salts thereof either alone or in combination threo isomers can be indicated as “threo” and the combined erythro isomers as “erythro”.

In accordance with the invention, formulations are provided which are to be taken by a subject and which do not initially administer the active agent when the subject first takes the formulation. However, at a later time point the agent is administered to the subject as a “pulse” of agent.

In relation to the treatment of sleep maintenance insomnia, the subject takes a formulation in accordance with the invention and which comprises a sleep inducing/maintaining agent. Initially, the agent is substantially not released from the formulation, but after a period of time, for example, when a subject suffering from sleep maintenance insomnia may be expected to wake up, the agent is released in a pulse, so as to treat the subject and reduce the likelihood of them waking up through the night. It is desired that the agent is released in a pulse like manner so that the drug does not remain in the subject's system for a long period of time, in order to ensure that the subject is able to wake up at a suitable time in the morning and not to feel drowsy, a common side-effect of sleep inducing/maintaining agents.

The L-HPC is preferably LH-11 or LH-21, especially LH-11. LH-11 and LH-21 are particular types of L-HPC and may be obtained from Shin-Etsu Chemical Co., Ltd., Tokyo, Japan. L-HPCs are insoluble in water and comprise a glucose backbone which is substituted to a minimal extent by hydroxypropyl groups LH-11 is mostly fibrous and has a mean particle size of 55 μm. LH-11 has a hydroxypropyl content of around 11% and a molecular weight of around 130,000. LH-21 is moderately fibrous and has a mean particle size of 45 μm. LH-21 has a molecular weight of around 120,000 and a hydroxypropyl content of around 11%

The wax may be any suitable wax such beeswax, carnuba wax, microcrystalline wax, hydrogenated castor oil. A particularly preferred wax is a glyceryl ester, such as glycerol behenate.

In a preferred formulation of the present invention as defined herein above, the wax and L-HPC are present in a ratio of 40:60 to 60:40 w/w. More preferably the ratio is 45:55 to 55:45 w/w, or 50:50 w/w. The skilled addressee will appreciate that with appropriate variation of the ratio, the delay in drug release can be tailored for a particular application. For example, a 50:50 w/w ratio of glycerol behenate as a wax, with LH-11 as the L-HPC employed as a delayed release layer in accordance with the present invention, is observed to provided a delayed release of approximately 3 hours. However, the same ratio with LH-21 as the L-HPC provides a delay in release of only 2 hours. Also reducing the amount of wax in comparison to the L-HPC is observed to reduce the delay significantly and conversely increasing the amount of wax to L-HPC ratio results in a significant increase in the delay of release. Thus with appropriate control of the ratio of wax to L-HPC and the type of wax/L-HPC, it is possible to control the time delay in release of the active agent, from a press-coated tablet comprising a delayed release layer surrounding a core comprising the active agent.

The delayed release layer surrounding the core may also comprise an amount of an active agent or agents, which may be the same or different to the active agent in the core, and which is designed to be released during dissolution/disintegration of the delayed release layer.

The subject to be treated is an animal, e.g. a mammal, especially a human.

The amount of active agent to be administered will be sufficient to be therapeutic or prophylactic. By therapeutic or prophylactic is meant one capable of achieving the desired response, and will be adjudged, typically, by a medical practitioner. The amount required will depend upon one or more of at least the active compound(s) concerned, the patient, the condition it is desired to treat or prevent and the formulation. However, it is likely to be in the order of from 1 μg to 1 g of compound per kg of body weight of the patient being treated.

Different dosing regimes may likewise be administered, again typically at the discretion of the medical practitioner. The formulation of the present invention may allow for at least daily administration although regimes where the compound(s) is (or are) administered more infrequently, e.g. every other day, weekly or fortnightly, for example, are also embraced by the present invention.

By treatment is meant herein at least an amelioration of a condition suffered by a patient; the treatment need not be curative (i.e. resulting in obviation of the condition). Analogously references herein to prevention or prophylaxis herein do not indicate or require complete prevention of a condition; its manifestation may instead be reduced or delayed via prophylaxis or prevention according to the present invention.

For use according to the present invention, the compounds or physiologically acceptable salt, solvate, ester or other physiologically acceptable functional derivative thereof described herein are presented in a press-coated tablet form comprising the compound or physiologically acceptable salt, ester or other physiologically functional derivative thereof, together with one or more pharmaceutically acceptable excipients therefore and optionally other therapeutic and/or prophylactic ingredients. Any excipients are acceptable in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

The tablets of the present invention may be prepared using reagents and techniques readily available in the art and/or exemplary methods as described herein.

The tablets include those suitable for oral, rectal or vaginal administration. The tablets may, where appropriate, be conveniently presented in discrete dosage units and may be prepared by any of the methods well known in the art of pharmacy.

Compressed tablets may be prepared by compressing the core tablet in a suitable machine an active compound in a free-flowing form such as a powder or granules optionally mixed with a binder, lubricant, inert diluent, lubricating agent, surface-active agent or dispersing agent. The core tablet is subsequently coated with the materials for forming the delayed release layer. Tablets may be optionally coated, for example, by way of a further gastro-resistant coating.

Tablets suitable for rectal administration are most preferably presented as unit dose suppositories. Suitable carriers include cocoa butter and other materials commonly used in the art. The suppositories may be conveniently formed by admixture of a tablet with the softened or melted carrier(s) followed by chilling and shaping in moulds.

The tablets of the present invention may be prepared using pharmaceutical processes namely by direct compression or by granulation processing and final tableting. The process may comprise the steps of initially forming a core comprising the active agent and subsequently surrounding core with the delayed release layer. The core may be formed by dispersing one or more active agents with one or more excipients, such as a cellulose ether, typically a L-HPC, such as LH-21.

The delayed release layer may be formed by melting the wax component and subsequently admixing the other components including the L-HPC. The mixture may then be allowed to cool and solidify before being ground and/or forced through a sieve, in order to achieve granules of the size range 500 μm-1 mm. The core may then be coated with the delayed release layer material by direct compression. Typically the core is sandwiched between top and bottom layers of the delayed release material and hence completely surrounds the core.

The tableting for the formulation of tablets may be conducted using an apparatus ordinarily employed for the formation or granulation of tablets. Examples may include single-punch tableting machine, rotary tableting machine and tableting tester.

Tableting is conducted usually under a pressure of 50 to 300 MPa, preferably 80 to 200 MPa. At a pressure less than 50 MPa, the resulting tablet may have insufficient hardness, which disturbs easily handling, while pressures exceeding 300 MPa may serve to cause a delay in disintegration.

The core and/or delayed release layer may include a filler, such as a water insoluble filler, water soluble filler, and mixtures thereof. The water insoluble filler, may be a calcium salt or talc. Exemplary water soluble fillers such as water soluble sugars and sugar alcohols, preferably lactose, glucose, fructose, mannose, galactose, the corresponding sugar alcohols and other sugar alcohols, such as mannitol, sorbitol, and xylitol.

The filler in the delayed release layer can be the same or different as the filler in the core composition, if any. For example, the core composition can include a water soluble filler while the press coat composition can include a water insoluble filler.

Other excipients can also be present in the core and/or delayed release layer, including lubricants (such as talc and magnesium stearate), glidants (such as fumed or colloidal silica), pH modifiers (such as acids, bases and buffer systems), and pharmaceutically useful processing aids. It will be appreciated that such other excipients may be the same or different in the core and delayed release layer, if any.

In a preferred embodiment of the invention, the core components (active agent and optional excipients) are blended together and compressed into suitable cores. The blending can take place in any order of addition. Preferably, the cores are blended by starting with the smallest volume component and then successively adding the larger volume components.

The tablet can be further coated with optional additional coatings. The additional coatings can be pH-dependent on pH-independent, aesthetic or functional; where the coating is a gastro-resistant coating (intended to prevent release in the stomach), the ‘clock’ or time for delayed release, as defined herein, will not start until gastric emptying occurs and dissolution of the gastro-resistant coating takes place (as can be determined, for example, by employing scintigraphy studies). The time taken for dissolution of the gastro-resistant coating together with the delay from the time-delay layer will ensure drug release in the lower reaches of the intestine, particularly the distal ileum and/or colon. Such additional coatings preferably include film forming materials. For subjects who may additionally find it difficult to go to sleep, the delayed release layer and/or additional coating may include a sleep inducing agent for immediate release.

DETAILED DESCRIPTION

The present invention will now be further described by way of example and with reference to the figure which show:

FIG. 1 shows the release profile of a drug from a tablet comprising glycerol behenate and LH-11 in a 50/50 w/w ratio in a delayed release layer;

FIG. 2 shows the release profile of a drug from a tablet comprising glycerol behenate and LH-21 in a 50/50 w/w ratio in a delayed release layer;

FIGS. 3 and 4 show the release profile of a drug from a tablet comprising glycerol behenate and LH-11 (FIG. 3) and LH-21 (FIG. 4) in 30:70 w/w ratio, in a delayed release layer;

FIG. 5 shows Gamma Scintigraphy Images showing release of delayed release formulation of Zolpidem;

FIG. 6 shows Pharmacokinetic analysis of drug levels in plasma, in 6 subjects; and

FIG. 7 shows the release profile of a tablet comprising a delayed release layer of 50/50 w/w glycerol behenate/LH32.

Formulation for Treating Sleep Maintenance Insomnia

1. Clinical Need

This formulation profile was designed as a treatment for people that fall asleep initially, then reawaken and are unable to sleep 2-3 hours later.

2. Methods

2.1. Core Tablet Blend and Core Tablet Compression

-   -   (i) 1 g Zolpidem tartrate, 5.1 g ac-di-sol, 2.0 g lactose and         0.9 g magnesium stearate. Powder mix of the above, except         magnesium stearate, for 10 min in turbula mixer, then magnesium         stearate added and all mixed for further 5 min.     -   (ii) 90 mg core tab blend-compressed in a 6.9 mm die/punch set         at 1 ton for 10 seconds.     -   (iii) Tablets are stored in amber glass bottle until use.         2.2. Granules (to Surround Core Tablet)     -   (i) Glycerol behenate (GB) and LH-11 weighed into tared weigh         boats according to Table 1:

TABLE 1 Excipient Weight (g) GB 10 LH-11 10

-   -   (ii) GB placed in a glass beaker on a hot plate set at 100° C.         Once the GB melted, LH-11 added gradually whilst stirring until         a uniform mix is achieved.     -   (iii) The mix stirred continuously until cooled to room         temperature. The granules are left for at least 30 min at room         temperature before the next step.     -   (iv) The cooled granules forced through a 1 mm sieve (using a         spatula and a brush) and collected on a 500 μm sieve so that the         granules used are in the size range 500 μm-1 mm.     -   (v) Granules stored in amber glass screw-top jar until use.         2.3. Formulation Compression     -   (i) A 13 mm die and matching flat-faced punches used to compress         the formulation. For 6 tablets, 12×250 mg granules (to surround         core tablet) are weighed into tared weigh boats.     -   (ii) 250 mg granules placed onto the lower punch, the core         tablet dropped on and centralised (centralising tool) before         placing the other 250 mg granules on top.     -   (iii) The formulation is compressed at 5 ton for 2 minutes in a         13 mm die/punch set.         2.4. Dissolution

Dissolution performed in 900 ml sodium phosphate buffer (0.01 M, at pH7) at 37° C., with UV analysis at 242 nm.

3. Results (50:50, GB:LH-11)

As can be seen from FIG. 1, a delay of approximately 3 hours is observed, followed by a rapid pulsed release of drug.

4. Supporting Data

4.1. LH-21 instead of LH-11 (50:50, GB:LH-21)

As can be seen in FIG. 2, substituting LH-11 for LH-21, results in a decrease in the delay of release time. Such a decrease may not be desired for all envisaged applications.

4.2. 80:20, GB:LH-11

No release of zolpidem core tablet over 12 hours, data not shown.

4.3. 80:20, GB:LH-21

No release of zolpidem core tablet over 12 hours, data not shown.

4.4. 30:70, GB:LH-11

As can be seen in FIG. 3, reducing the glycerol behenate to LH-11 ratio results in a significant decrease in the delay of release time.

4.5. 30:70, GB:LH-21

As can be seen in FIG. 4, reducing the glycerol behenate to LH-21 ratio results in a significant decrease in the delay of release time.

Using LH-21 in the outer granules instead of LH-11 releases the core tablet approximately 30 min earlier in both examples shown above.

Extraction Method/Analysis of Plasma Levels of Zolpidem

Materials

Human plasma, lithium heparin, origin USA: Sera laboratories international Ltd, Bx H911239 Zolpidem tartrate

DEE: Fisher laboratory reagent grade Bx 1097413

NaOH: prepared using Q3 water and NaOH: Sigma Aldrich, reagent grade beads, 97% Bx 01209BH

Method

vortex blank plasma

add 400 ul blank plasma to glass screw cap tubes

Calibration

Blank preparation—to be prepped before standards

add 100 ul mobile phase to 400 ul blank plasma

vortex 10 secs

add 50 ul 1M NaOH

vortex 10 secs

add 4 mL DEE and vortex 3 mins (note: DEE decanted from bottle fresh every day)

pipette tips changed after every addition of mobile phase/DEE

Standard Preparation

Starting with lowest concentration standard, vortex standard

Add 100 ul standard to 400 ul blank plasma

Vortex 10 secs

Add 50 ul 1M NaOH

Vortex 10 secs

Add 4 mL DEE and vortex 3 mins (note: DEE decanted from bottle fresh every day)

Pipette tips changed after every addition of standard/DEE

Centrifuge samples 3 mins at 2000 rpm

Remove top layer into clean labelled glass screwtop tube using glass pipette

Evaporate to dryness under nitrogen at 40° C. (also used RVC to evaporate, 40° C., 100 mbar, 25 mins)

Reconstitute in 100 ul mobile phase. Allow to stand for 30 mins and then vortex 3 mins

Transfer to HPLC vial with insert

Sample Preparation

Vortex samples to mix

Add 500 ul sample to glass screwtop tube

Add 50 ul 1M NaOH

Vortex 10 secs

Add 4 mL DEE and vortex 3 mins (note: DEE decanted from bottle fresh every day)

Pipette tips changed after every addition of standard/DEE

Centrifuge samples 3 mins at 2000 rpm

Remove top layer into clean labelled glass screwtop tube using glass pipette

Evaporate to dryness under nitrogen at 40° C. (also used RVC to evaporate, 40° C., 100 mbar, 25 mins)

Reconstitute in 100 ul mobile phase. Allow to stand for 30 mins and then vortex 3 mins

Transfer to HPLC vial with insert

Mobile Phase Preparation

Materials

Potassium phosphate monobasic, SAFC lot 1370660

NaOH: Sigma Aldrich, reagent grade beads, 97% Bx 01209BH

Acetonitrile: Fisher HPLC gradeBx 1095614

20 mM potassium phosphate buffer prepared with Q3 water, adjusted to pH 6 with NaOH

Buchner filtered through 0.2 um 47 mm nylon membrane

Chromatographic Conditions

Gynkotek HPLC system with Perkin Elmer LS 40 fluorescence detector

Column: phenomenex Lichrospher RP-18 100A 125×4.00 mm 5 micron with guard column

Detection: excitation: 251 nm emission: 289

Gradient: starting conditions 60% buffer 40% acetonitrile flowrate 1 mL/min

Increase from 40-80% acetonitrile over 10 mins, hold at 80% for 4 mins

Return to starting conditions for 2 mins prior to next injection

Injection volume 20 uL

Spiked Standard Range

1-150 ng/mL plasma

Clinical Trial Protocol—Zolpidem 10 mg Delayed-Release (2 Hour Time-Delay)

Clinical studies were carried out in Healthy male volunteers aged between 18-65 years inclusive with a body mass index (BMI) between 18.0 and 29.9 kg/m².

Gastrointestinal transit of the delayed-release tablets was characterised by inclusion of a radiolabel marker, technetium-99m (^(99m)Tc), complexed with diethylenetriaminepentaacetic acid (DTPA) which prevents absorption from the gastrointestinal tract. The radiolabel is incorporated into the core tablet. Each tablet was radiolabelled with 4 MBq 99 mTc-DTPA and administered with 240 ml of water at bedtime.

Subjects received a standard dinner comprising roast chicken with salad, low fat yoghurt and one cup of decaffeinated tea, coffee or juice 4 hours prior to dosing.

Scintigraphic imaging was performed using a Siemens E-Cam gamma camera fitted with a low-energy high-resolution collimator. Subjects were imaged in a standing position except during periods of sleep where the subjects were imaged lying down.

The following imaging schedule was used:

Anterior static acquisitions of 25-second duration each were collected immediately after dosing then every 15 minutes until complete release of radiolabel marker.

A 5 mL pre-dose blood sample was taken from each subject 15 minutes before dosing. Following dosing blood samples were taken according to the following schedule:

Every 15 minutes until burst release observed by scintigraphy then every 15 minutes for 2 hours then every 30 minutes for 1 hour then hourly until end of study day (9 hours post-dose). See FIG. 5.

Blood samples were centrifuged at 2000 g for 10 minutes and the plasma fraction removed and stored at −20° C. for subsequent analysis. See FIG. 6.

FIG. 7 shows the release profile of a tablet formulation comprising a delayed release layer of 50/50 w/w glycerol behenate/LH32 demonstrating the ability to vary the period of delay before pulsed drug release. 

The invention claimed is:
 1. A press-coated tablet formulation for a delayed, followed by a pulsed release of an active agent, the tablet comprising: (a) a core comprising the active agent(s) together with an excipient(s); and (b) a delayed release layer surrounding the core and consisting essentially of granules having a size of from 500 μm to 1 mm as measured by sieves; said granules comprising a wax and particles of a low-substituted hydroxypropyl cellulose (L-HPC) in a ratio of 40:60 to 60:40 w/w; wherein the delayed release layer substantially delays release of the active agent within the core for between 3-8 hours after administration of the tablet to a subject and thereafter a pulsed release of the active agent from the core occurs, such that at least 70% of the active agent in the core is released within 5-80 minutes; wherein the L-HPC has a mean particle size of 55 μm, a hydroxypropyl content of 11%, and a molecular weight of 130,000, or a mean particle size of 20 μm, a hydroxypropyl content of 8%, and a molecular weight of 115,000.
 2. The press-coated tablet according to claim 1 further comprising an amount of an active agent, which is the same or different to the active agent in the core, in the delayed release layer.
 3. The press-coated tablet according to claim 1 wherein the active agent is designed to treat sleep maintenance insomnia.
 4. The press-coated tablet according to claim 3 wherein the active agent is a sedative or hypnotic selected from the group consisting of zolpidem, Zaleplon and Zopiclone.
 5. A method of treating sleep maintenance insomnia, the method comprising administering a press-coated tablet according to claim 3 comprising a sleep inducing agent to a subject immediately before the subject intends sleeping.
 6. The method according to claim 5 wherein the sleep inducing agent is selected from the group consisting of zolpidem, Zaleplon and Zopiclone.
 7. The method according to claim 5 wherein delayed release of the sleep inducing agent is achieved by providing a press-coated tablet comprising a delayed release layer surrounding a core comprising the sleep inducing agent.
 8. The method according to claim 7 wherein the delayed release layer comprises a wax and a low-substituted hydroxypropyl cellulose (L-HPC), wherein the L-HPC has a mean particle size of 20 μm, a hydroxypropyl content of 8%, and a molecular weight of 115,000.
 9. The method according to claim 7 wherein the delayed release layer comprises a wax and a low-substituted hydroxypropyl cellulose (L-HPC), wherein the L-HPC has a mean particle size of 55 μm, a hydroxypropyl content of 11%, and a molecular weight of 130,000.
 10. The press-coated tablet according to claim 1 wherein the L-HPC has a mean particle size of 55 μm, a hydroxypropyl content of 11%, and a molecular weight of 130,000.
 11. The press-coated tablet according to claim 1 wherein the wax is selected from the group consisting of beeswax, carnuba wax, microcrystalline wax, a hydrogenated castor oil, and a glyceryl ester.
 12. The press-coated tablet according to claim 11 wherein the glyceryl ester is glycerol behenate.
 13. The press-coated tablet according to claim 1 wherein the wax and L-HPC are present in a ratio of 45:55 to 55:45 w/w.
 14. The press-coated tablet according to claim 1 further comprising one or more pH dependent, pH-independent, aesthetic or functional coatings.
 15. The press-coated tablet according to claim 14 wherein the coating is a gastro-resistant coating.
 16. A press-coated tablet according to claim 1, comprising a sedative or hypnotic agent for treating sleep maintenance insomnia, wherein the tablet is intended to be administered immediately prior to a subject going to sleep.
 17. The press-coated tablet according to claim 16 wherein the press-coated tablet comprises a delayed release layer surrounding a core comprising the sedative or hypnotic agent.
 18. The press-coated tablet according to claim 1, comprising one or more of the following active agents: Antacids selected from the group consisting of aluminum hydroxide, magnesium carbonate, magnesium trisilicate, hydrotalcite, and simeticonealginates; Antispasmodics selected from the group consisting of atropine sulphate, dicycloverine hydrochloride, hyoscine butylbromine, propantheline bromide, alverine citrate, and mebeverine hydrochloride; Motility stimulants selected from the group consisting of metoclorpramide and domperidone; H2-Receptor antagonists selected from the group consisting of Cimetidine, famotidinenizatidine, and ranitidine; Antimuscarinics; Chelates selected from the group consisting of Tripotassium dicitratbismuthate and sucralfate; Prostaglandin analogues; Aminosalicylates selected from the group consisting of balsazide sodium, mesalazine, olsalazine, and sulphasalazine; Corticosteroids selected from the group consisting of beclometasone dipropionate, budenoside, hydrocortisone, and prednisolone; Affecting immune response selected from the group consisting of ciclosporin, mercaptopurine, methotrexate, adalimumab, and infliximab; Stimulant Laxatives selected from the group consisting of bisacodyl, dantron, docusate, and sodium picosulfate; Drugs affecting biliary composition and flow; Bile acids sequestrants selected from the group consisting of colestyramine, Oxyphencyclimine, Camylofin, Mebeverine, Trimebutine, Rociverine, Dicycloverine, Dihexyverine, Difemerine, Piperidolate, Benzilone, Mepenzolate, Pipenzolate, Glycopyrronium, Oxyphenonium, Penthienate, Methantheline, Propantheline, Otilonium bromide, Tridihexethyl, Isopropamide, Hexocyclium, Poldine, Bevonium, Diphemanil, Tiemonium iodide, Prifinium bromide, Timepidium bromide, Fenpiverinium, Papaverine, Drotaverine, Moxaverine, 5-HT3 antagonists, 5-HT4 agonists, Fenpiprane, Diisopromine, Chlorbenzoxamine, Pinaverium, Fenoverine, Idanpramine, Proxazole, Alverine, Trepibutone, Isometheptene, Caroverine, Phloroglucinol, Silicones, Trimethyldiphenylpropylamine, Atropine, Hyoscyamine, Scopolamine, Butylscopolamine, Methylscopolamine, Methylatropine, Fentonium, Cimetropium bromide, and primarily dopamine antagonists; Proton pump inhibitors selected from the group consisting of Omeprazole, lansoprazole, pantoprazole, esomeprazole, and rabeprazole sodium; Opioids and opioid receptor antagonists; Analgesics selected from the group consisting of Acetaminophen, Diclofenac, Diflunisal, Etodolac, Fenoprofen, Flurbiprofen, Ibuprofen, Indomethacin, Ketoprofen, Ketorolac, Meclofenamate, Mefenamic Acid, Meloxicam, Nabumetone, Naproxen, Oxaprozin, Phenylbutazone, Piroxicam, Sulindac, Tolmetin, Celecoxib, Buprenorphine, Butorphanol, Codeine, Hydrocodone, Hydromorphone, Levorphanol, Meperidine, Methadone, Morphine, Nalbuphine, Oxycodone, Oxymorphone, Pentazocine, Propoxyphene, and Tramadol; Sleep drugs selected from the group consisting of Nitrazepam, Flurazepam, Loprazolam, Lormetazepam, Temazepam, Zaleplon, Zolpidem, Zopiclone, Chloral Hydrate, Triclofos, Clomethiazole, Quazepam, triazolam, Estazolam, Clonazepam, Alprazolam, Eszopiclone, Rozerem, Trazodone, Amitriptyline, Doxepin, Benzodiazepine drugs, melatonin, diphenhydramine, and herbal remedies; Cardiac glycosides selected from the group consisting of Digoxin and digitoxin; Phosphodiesterase inhibitors selected from the group consisting of enoximone and milrinone; Thiazides and related diuretics selected from the group consisting of bendroflumethiazide, chlortalidone, cyclopenthiazide, inapamide, metolazone, and xipamide; Diuretics selected from the group consisting of furosemide, bumetanide, and torasemide; Potassium sparing diuretics and aldosterone antagonists selected from the group consisting of amiloride hydrochloride, triamterene, weplerenone, and spironolactone; Osmotic diuretics; Drugs for arrhythmias selected from the group consisting of adenosine, amiodarone hydrochloride, disopyramide, flecainide acetate, propafenone hydrochloride, and lidocaine hydrochloride; Beta adrenoreceptor blocking drugs selected from the group consisting of propanalol, atenolol, acebutolol, bisprolol fumarate, carvedilol, celiprolol, esmolol, lebatolol, metoprolol tartrate, nadolol, nebivolol, oxprenolol, pindolol, solatol, and timolol; Hypertension drugs selected from the group consisting of ambrisentan, bosentan, diazoxide, hydralazine, iloprost, minoxidil, sildenafil, sitaxentan, sodium nitroprusside, clonidine, methyldopa, moxonidine, guanethidine monosulphate, doxazosin, indoramin, prazosin, terazosin, phenoxybenzamine, and phentolamine mesilate; Drugs affecting the renin-angiotensin system selected from the group consisting of Captropril, Cilazapril, Enalapril Maleate, Fosinopril, Imidapril, Lisinopril, Moexipril, Perindopril Erbumine, Quinapril, Ramipril, Trandolapril, Candesartan Cilexetil, Eprosartan, Irbesartan, Losartan, Olmesartan Medoxomil, Telmisartan, Valsartan, and Aliskiren; Nitrates, calcium channel Blockers, and antianginal drugs selected from the group consisting of Glyceryl trinitrate, Isosorbide Dinitrate, Isosorbide Mononitrate, Amlodipine, Diltiazem, Felodipine, Isradipine, Lacidipine, Lercanidipine, Nicardipine, Nifedipine, Nimodipine, Verapamil, Ivabradine, Nicorandil, and Ranolazine; Peripheral Vasodilators and related drugs selected from the group consisting of Cilostazol, Inositol Nicotinate, Moxisylyte, Naftidrofuryl Oxalate, and Pentoxifylline; Sympathomimetics selected from the group consisting of Dopamine, Dopexamine, Ephedrine, Metaraminol, Noradrenaline Acid Tartrate, Norephidrine Bitartrate, and Phenylephidrine; Anticoagulants and Protamine selected from the group consisting of Heparin, Bemiparin, Dalteparin, Enoxaparin, Tinzaparin, Danaparoid, Bivalirudin, Lepirudin, Epoprostenol, Fondaprinux, Warfarin, Acenocoumarol, Phenindione, Dabigatran Etexilate, Rivaroxaban, and Protamine Sulphate; Antiplatelet Drugs selected from the group consisting of Abciximab, Aspirin, Clopidogrel, Dipyridamole, Eptifibatide, Prasugrel, and Tirofiban; Fibrinolytic and antifibrinolytic drugs selected from the group consisting of Alteplase, Reteplase, Streptokinase, Tenecteplase, Urokinase, Etamsylate, and Tranexamic Acid; Lipid Regulating Drugs selected from the group consisting of Atorvastatin, Fluvastatin, Pravastatin, Rosuvastatin, Simvastatin, Colesevam, Colestyramine, Colestipol, Ezetimibe, Bezafibrate, Ciprofibrate, Fenofibrate, Gemfibrozyl, Acipmox, Nictotinic Acid, Omega three fatty acid compounds, Ethanolamine Oleate, and Sodium Tetradecyl Suphate; CNS Drugs selected from the group consisting of Benperidol, Chlorpromazine, Flupentixol, Haloperidol, Levomepromazine, Pericyazine, Perphenazine, Pimozide, Prochlorperazine, Promazine, Sulpiride, Trifluoperazine, Zuclopenthixol, Amisulpride, Aripiprazole, Clozapine, Olanzapine, Paliperidone, Quetiapine, Riperidone, Sertindole, Zotepine, Flupentixol, Fluphenazine, Olanzapine Embonate, Pipotiazine Palmitate, Risperidone, Zuclopenthixol Decanoate, Carbamazepine, Valproate, Valproic acid, Lithium Carbonate, Lithium Citrate, Amitriptyline, Clomipramine, Dosulepin, Imipramine, Lofepramine, Nortriptyline, Trimipramine, mianserin, Trazodone, Phenelzine, Isocarboxazid, Tranylcypromine, Moclobemide, Citalopram, Escitalopram, Fluoxetine, Fluvoxamine, Paroxetine, Sertraline, Agomelatine, Duloxetine, Flupentixol, Mirtazapine, Reboxetine, Trytophan, Venflaxine, Atomoxetine, Dexametamine, Methylphenidate, Modafinil, Eslicarbazepine, Ocarbazepene, Ethosuximide, Gabapentin, Pregabalin, Lacosamide, Lamotrigine, Levetiracetam, Phenobarbital, Primidone, Phenytoin, Rufinamide, Tiagabine, Topiramate, Vigabatrin, Zonisamide, ropinirole, Rotigotine, Co-Beneldopa, Levodopa, Co-Careldopa, Rasagiline, Selegiline, Entacapone, Tolcapone, Amantidine, Orphenadrine, Procyclidine, Trihexyphenidyl, Haloperidol, Piracetam, Riluzole, Tetrabenazine, Acamprosate, Disulfiram, Bupropion, Vareniciline, Buprenorphine, Lofexidine, Donepezil, Galantamine, Memantine, and Rivastigimine; Anti-Infectives selected from the group consisting of Benzylpenicillin, Phenoxymethylpenicillin, Flucloxacillin, Temocillin, Amoxicillin, Ampicillin, Co-Amoxiclav, Co-Fluampicil, Piperacillin, Ticarcillin, Pivmecillinam, Cephalosporins, Cefaclor, Cefadroxil, Cefalexin, Cefixime, Cefotaxime, Cefradine, Ceftazidime, Cefuroxime, Ertapenem, Imipenem, Meropenem, Aztreonam, Tetracycline, Demeclocycline, Doxocycline, Lymecycline, Minocycline, Oxytetracycline, Tigecycline, Gentamicin, Amikacin, Neomycin, Tobramycin, Erythromycin, Azithromycin, Clarithromycin, Telithromycin, Clindamycin, Chloramphenicol, Fusidic Acid, Vancomycin, Teicoplanin, Daptomycin, Linezolid, Quinupristin, Colistin, Co-Trimoxazole, Sulpadiazine, Trimethoprim, Capreomycin, Cycloserine, Ethambutol, Isoniazid, Pyrazinamide, Rifabutin, Rifampicin, Streptomycin, Dapsone, Clofazimine, Metronidazole, Tinidazole, Ciproflaxacin, Levoflaxacin, Moxifloxacin, Nalidixic Acid, Norflaxine, Orflaxacin, Nitrofurantoin, Methenamine Hippurate, Amphotericin, Anidulafungin, Caspofungin, Fluconazole, Flucytosine, Griseofluvin, Itraconzole, Ketoconazole, Micafungin, Nystatin, Posaconazole, Terbinafine, Voriconazole, Abacavir, Didanosine, Emtricitabine, Lamivudine, Stavudine, Tenofovir Disoproxil, Zidovudine, Atazanavir, Darunavir, Fosamprenavir, Indinavir, Lopinair, Nelfinavir, Ritonavir, Saquinavir, Tipranavir, Efavirenz, Etravirine, Nevarapine, Enfuvirtide, Maraviroc, Raltegravir, Aciclovir, Famciclovir, Inosine Pranobex, Valaciclovir, Cidofovir, Gangciclovir, Foscarnet, Valgangciclovir, Adefovir Dipivoxil, Entecavir, Telbivudine, Amantadine, Oseltamivir, Zanamivir, Palivizumab, Ribavirin, Artemether, Chloroquine, Mefloquine, Primaquine, Proguanil, Pyrimethamine, Quinine, Doxycyclin, Diloxanide Furoate, Metronidaziole, Tinidazole, Mepacrine, Sodium Stibogluconate, Atovaquone, Pentamidine Isetionate, Mebendazole, and Piperazine; Other drugs selected from the group consisting of Benztropine, procyclidine, biperiden, Amantadine, Bromocriptine, Pergolide, Entacapone, Tolcapone, Selegeline, Pramipexole, budesonide, formoterol, quetiapine fumarate, olanzapine, pioglitazone, montelukast, Zoledromic Acid, valsartan, latanoprost, Irbesartan, Clopidogrel, Atomoxetine, Dexamfetamine, Methylphenidate, Modafinil, Bleomycin, Dactinomycin, Daunorubicin, Idarubicin, Mitomycin, Mitoxantrone, Azacitidine, Capecitabine, Cladribine, Clofarabine, Cytarabine, Fludarabine, Flourouracil, Gemcitabine, mercaptopurine, methotrexate, Nelarabine, Pemetrexed, Raltitrexed, Thioguanine, Apomorphine, Betamethasone, Cortisone, Deflazacort, Dexamethosone, Hydrocortisone, Methylprednisolone, Prednisolone, Triamcinolone, Ciclosporine, Sirolimus, Tacrolimus, Interferon Alpha, and Interferon Beta.
 19. The press-coated tablet according to claim 18, comprising one or more of the following active agents: pirenzepine, misoprostol, ursodeoxycholic acid, Alosetron, Cilansetron, Mosapride, Prucalopride, Tegaserod, Metoclopramide, Bromopride, Clebopride, Domperidone, Alizapride, Cinitapride, Cisapride, Codeine, Morphine, loperamide, diphenoxylate, methylnaltrexone bromide, Valerian, and mannitol.
 20. The press-coated tablet according to claim 1, wherein the L-HPC has a mean particle size of 20 microns, a hydroxypropyl content of 8%, and a molecular weight of 115,000.
 21. A press-coated tablet formulation for a delayed, followed by a pulsed release of an active agent, the tablet comprising: (a) a core comprising the active agent(s) together with an excipient(s); and (b) a delayed release layer surrounding the core and consisting essentially of granules having a size of from 500 μm to 1 mm as measured by sieves; said granules comprising a wax and particles of a low-substituted hydroxypropyl cellulose (L-HPC) in a ratio of 40:60 to 60:40 w/w; wherein the delayed release layer substantially delays release of the active agent within the core for between 3-8 hours after administration of the tablet to a subject and thereafter a pulsed release of the active agent from the core occurs, such that at least 70% of the active agent in the core is released within 5-80 minutes; wherein the L-HPC has a mean particle size of 55 μm, a hydroxypropyl content of 11%, and a molecular weight of 130,000, or a mean particle size of 20 μm, a hydroxypropyl content of 8%, and a molecular weight of 115,000; wherein the delay in release is measured in 900 ml sodium phosphate buffer (0.01 M, at pH7) at 37° C., with UV analysis.
 22. The press-coated tablet according to claim 16 wherein the sedative or hypnotic agent is selected from the group consisting of zolpidem, Zaleplon and Zopiclone. 